Electrical measuring instrument.



No. 768,957. PATENTED AUG. 30, 1904. H. C SNCO'K;-

ELECTRICAL MEASURING INSTRUMENT.

APPLICATION FILED JUNE 17, 1904.

N0 MODEL.

UNITED STATES Patented August 30, 1904.

PATENT Trice.

HOMER CLYDE SNOOK, OF PHILADELPHIA, PENNSYLVANIA, ASSIGNOR TO ROENTCENMANUFACTURING COMPANY, OF PHILADELPHIA, PENN- SYLVANIA, A CORPORATION OFPENNSYLVANIA.

ELECTRICAL MEASURING INSTRUMENT.

SPECIFICATION forming part of Letters Patent No. 768,957, dated August30, 1904.

Application filed June 17, 1904. Serial No. 212.9%. (No model.) i

To all 11:72 m it may concern:

Be it known that I, HOMER CLYDE SNooK, residing at Philadelphia,in thecity and county of Philadelphia and State of Pennsylvania,

have invented a new and useful Electrical Measuring Instrument, of whichthe following is a specification.

My invention relates to electrical measuring instruments, and moreespecially to an in- IQ strument adaptedto be used with high-potentialcircuits or circuits traversed by relatively short impulses of current,such impulses succeeding each other at relatively great intervals oftime.

I 5 My invention comprises a combination of means whereby themeasurement of electrical quantities may be made in connection withcircuits over which pass high-potential impulses, and more particularlyunidirectional impulses.

In one of its aspects my invention comprises an electrical measuringinstrument for use with circuits over which pass currents derived fromthe secondaries of induction or 2 5 Ruhmkorff coils or the like.

Reference is to be had to the accompanying drawings, which illustrateone embodiment of my invention, an ammeter for the measurement ofcurrents passed through an X-ray or 3 similar tube being shown.

In said drawings, Figure l is aview, partly diagrammatic, of themeasuring instrument. Fig. 2 is a diagrammatic view of circuits andapparatus illustrating my invention. Fig. 3 is a graphic representationof a current impulse in the primary of the induction-coil. Fig. 4c is agraphic representation of the current resulting in the secondary.

Referring to Fig. 1, M represents a per- 4 manent magnet having thepole-pieces p whose inner surfaces are portions of the same cylinder.Secured to the pole-pieces and supported concentrically with the innerpolar surfaces is the internal magnetic core 0. In

the narrow annular space between the inner polar surfaces and the core 0is mounted the coil 0, which rotates within the magnetic field whencurrent passes through its winding.

The coil a carries the indicator or pointer a, which moves over agraduated scale or dial, 5 thus indicating magnitudes of electricalquantities.

The mechanism as thus far described is known in the art as aDeprez-DArsonval galvanometer. In instruments of this kind the movablecoil a is wound upon a frame of copper or aluminium, either sheet orwire, which serves as a damping means to render the instrumentdead-beat, the coil and frame being delicately mounted on pivots bearingin jewels, the current being led into and out of the winding of the coilby means of flat spiral springs connected at their inner ends to thecoil-pivots and at their outer end to abutments. Such instrument hasheretofore been 5 used for measuring continuous currents asdistinguished from unidirectional impulses following each other atrelatively great time intervals. Furthermore, such instruments haveheretofore been capable of use on circuits of 7 low or moderately highpotentials only. By the means hereinafter described, however, I havebeen able to transform such instrument of theprior art into one capableof measuring unidirectional impulses which succeed each other atrelatively great time intervals and in connection with circuits of highor very high potentials, such as derived from induction-coils orRuhmkorff coils capable of giving sparks through air having a length of30 from several inches up to thirty or more inches, representingvoltages or potentials as high as several hundreds of thousands ofvolts. This transformation of the instrument of the prior art into theinstrument herein claimed 5 results from several innovations andfeatures, without which the instrument of the prior art would be uselessand would, in fact, be destroyed or burned out if it were attempted touse such instrument to measure high-poten- 9 tial impulses.

The right-hand portion of Fig. 1 illustrates diagrammatically themovable coil a in shunt, to which is connected the condenser C and theresistance R, comprised of highly-insulated conductor non-inductivelywound. The repulses.

sistance-bobbins, wound non-inductively, as comnmnly used in thelow-potential electrical measuring instruments, will not serve for theresistance R of the instrument herein described. It is necessary toespecially wind the resistance R in a manner insuring great insulationbetween the neighboring parts of the wire. 1f wound as heretoforepracticed in low-potential instruments, sparking will occur betweenneighboring convolutions or layers, with the result that a substantialerror will be introduced into the reading of the instrument. 7/7) arethe binding-posts of the instrument. One terminal of the movable coil (tis connected electrically with the magnet M, and therefore also with theinternal core 0, by means of the conductor f. When the instrument ismounted within a metallic casing, electrical connection is also madefrom the same terminal of the coil a with such casing. Similarly, anelectrical connection is made between the same terminal of the coil iand the copper or aluminium damping-frame,

(represented diagrammatically by (Z in Fig. 1.) The electricalconnection between the damping-frame and one terminal of the coil to isnot essential as long as a condenser C is connected in shunt to the coil(0. The conductor j, which connects one terminal of the coil (4 with allthe juxtaposed metallic or conducting parts, including magnet M, core 0,and the casing of the instrument, is a means whereby the electrostaticpotential of the coil a is maintained the same as that of allneighboring parts. In other words, by thus connecting one terminal ofthe coil (0 with the juxtaposed conducting parts, such as magnet andeasing, such juxtaposed parts rise to the high potential with the coil(0, and in consequence there will be no sparking from the body of thecoil (1. to the surrounding parts. Such sparking would ruin theinstrument and make it useless for measuring high-potential im- Thecondenser C serves also to pre vent sparking between neighboringconvolutions of the coil c and to operate as a holdover device orreservoir, whereby current through the coil (6 persists for a longertime than the impulse which traverses the circuit.

Referring to Fig. 3, the portion 1 of the curve therein shown representsthe rise of a direct current in the primary of an inductioncoil.Distances along the axis 0 1/ represent current magnitudes, anddistances along the axis 0 m represent times. Due to the self-inductionof the primary of the induction-coil the current does not gain its fullvalue instantly, but rather after a considerable time, (representedapproximately by 0 At 3 the current is broken at the interrupter in theprimary circuit and falls suddenly to Zero value, and then occur severalsmall oscillations, as 4, probably due to the condenser in shun-t to theinterrupter. The result in the secondary circuit is graphicallyrepresented in Fig. 4. The small inverse current d no to the rise ofcurrent of primary may be represented by the portion 5. hen the currentbreaks in the primary, there is a sudden direct impulse 6 of greatamplitude, but very short duration. This impulse is followed by severalimpulses 7, corresponding to the short primary impulses 4. It is theseimpulses (5 which are used in X-ray and similar work, and it is theseimpulses which may be measured by the instrument illustrated in Fig. 1.The condenser C is charged by each impulse 6, a portion of such impulseflowing simultaneously through the resistance R, the coil (1/ beingtraversed by a current dependent upon the difference of potential acrossthe terminals of the resistance B. After the impulse has passed andbefore the succeeding impulse the condenser C discharges through it anda, the effect being to prolong the period of time during which currentis flowing through the coil 1!. The condenser C may be replaced by someother condenser-like device, such as an electrolytie device or smallstoragecell. However, a mica condenser is preferred.

Referring to Fig. 2, P represents the primary of an induction orRuhmkorii' coil, whose secondary is represented at S. r 7 representterminals of the usual spark-gap. in

I circuit with the secondary S are included in series with each otherthe several small s parkgaps s s, the ventral-tube V, the X-ray tube X,and the instrument A, as shown in Fig. 1. The ventral-tube V serves tosuppress all impulses in the secondary circuit except the directimpulses, such as 6. The inverse impulses 5 are to a greater or lessextent suppressed by the ventral-tubeV, such tube being in the nature ofan asymmetrical resist ance and may be replaced by any device ofleringgreater resistance to a current flowing in a given direction than itoffers to a current flowing in the opposite direction. The spark-gaps sa serve also to suppress the inverse impulses, as 5, and weak impulses,as 7, because the potential of such impulses is too small to cause aspark to leap across such gaps, while the impulses 6 are of exceedinglyhigh potential and easily leap such gaps. The ammeter is connectedintermediate the X-ray tube X and the negative terminal of the secondaryS as its preferred position, for when connected between the positiveterminal of the secondary S and the tube X suflicient static charge willcollect on the conductors intermediate such positive terminal and theremainder of the circuit to cause a slight indication to be registeredby the needle 1/, even though no current is passing through the tube X.It follows that in the circuit of the secondary S only unidirectionalimpulses of high potential pass. These the instrument A measures, theindications serving to inform the operator as to the intensity orquantity of X-rays emitted, as well to 111- form him of the condition ordegree of vacuum in the tube X.

From the foregoing description it is seen that a direct-readingelectrical measuring instrument is provided, and which operates on themagnetic principle as distinguished from the hot wire or electrostaticinstruments, which have features of serious disadvantage.

It is apparent that the instrument herein described is portable andoccupies no more plied by fluctuating or alternating currents,

as well as by continuous currents. It is to be understood also that myinvention is not limited to an instrument having a permanent magnet, butthat it is equally applicable to an instrument having an electromagnetfor producing or maintaining the magnetic field, and that it isapplicable as well to an electrodynamometer instrument, in which casethe condenser C may be connected in shunt to the movable coil, the fixedcoil, or to both the fixed and movable coils. My invention is applicablealso to instruments in which the winding is a stationary one, themovable part being a magnetic vane, needle, or the like. In such casealso the condenser C will be connected in shunt to such stationarywinding, and in all cases the winding and parts traversed by theimpulses or which are in elec trical communication with thehigh-potential circuit will be electrically connected to all juxtaposedconducting parts. It is to be understood also that the resistance R maybe omitted in some cases and a relatively great resistance connected inseries with the coil (0. In the alternate forms of instruments abovementioned the resistance B may be connected in parallel with the windingor coil, or a relatively great resistance may be connected in serieswith such winding or coil. It is to be understood also that in additionto resistance R of the instrument shown in Fig. 1 or of the alternatetypes of instruments a resistance may be connected in series with thewinding or coil (1 lVhat I claim is- 1. In combination, means forproducing a magnetic held, a winding associated with said means, meansfor maintaining said winding at the same potential with juxtaposedparts, a condenser in shunt to said winding, and means for indicatingthe extent of reaction between said magnetic field and the fieldproduced by a current passed through said winding.

2. In combination, means for producing a magnetic field, a windingassociated with said means, means for maintaining said winding at thesame potential with juxtaposed parts,

magnetic field, a winding associated with said field, means formaintaining said winding and said field -produc1ng means at the samepotential, a resistance in shunt to said winding, and

means for indicating the extent of reaction between said magneticfieldand the field produced by current passed through said winding.

4:. In combination, means for producing magnetic field, a windingassociated with said field, means for maintaining said winding and saidfield-producing means at the same potential, a condenser in shunt withsaid winding, a resistance in shunt with said winding, and means forindicating the extent of reaction between said magnetic field and thefield produced by current passed through said winding.

5. In combination, means for producing a magneticfield, a windingassociated with said means, means for maintaining said winding at thesame potential with juxtaposed parts, and means for indicating theextent of reaction between said magnetic field and the field produced bya current passed through said winding.

6. In combination in an instrument for measuring high-potentialimpulses, means for producing a magnetic field, a winding associatedwith said means, means for maintaining said winding at the samepotential with juxtaposed parts, means for prolonging the impulses insaid winding, and means for indicating the extent of reaction betweensaid magnetic field and the field produced by said impulses passedthrough said winding.

7. In combination in an instrument for measuring high-potentialimpulses, means for producing a magnetic field, a winding associatedwith said means, means for maintaining said winding at the samepotential with juxtaposed parts, a non-inductive resistance in shunt tosaid winding, means for prolonging theimpulses through said winding, andmeans for indicating the extent of reaction between said magnetic fieldand the field produced by said impulses passed through said winding.

8. In combination, in an instrument for measuring high-potentialimpulses, a permanent magnet, a winding associated therewith, means formaintaining said winding at the same potential with juxtaposed parts,and means for indicating the extent of reaction beween the field of saidpermanent magnet and the field produced by impulses passed through saidwinding.

9. In combination in an instrument for measuring electrical impulses, apermanent magnet, a winding associated therewith, a condenser in shuntto said winding, and means for indicating the extent of reaction betweenthe field of said permanent magnet and the field produced by impulsespassed through said winding.

10. In combination in an instrument for measuring high-potentialimpulses, a permanent magnet, a winding associated therewith, means formaintaining said winding at the same potential with juxtaposed parts, acondenser in shunt to said winding, and means for indicating the extentof reaction between the field of said permanent magnet and the fieldproduced by the impulses passed through said winding.

11. In combination in an instrument for measuring electrical impulses, apermanent magnet, a winding associated therewith, a condenser in shuntto said winding, a non-inductive resistance in shunt to said winding,and means for indicating the extent of reaction between the field ofsaid permanent magnet and the field produced by the impulses passedthrough said winding.

12. In combination in an instrument for measuring high-potentialimpulses, a permanent magnet, a winding associated therewith, means formaintaining said winding at the same potential with juxtaposed parts, anoninductive resistance in shunt to said winding, a condenser in shuntto said. winding, and means for indicating the extent of reactionbetween the field of said pern'ianent magnet and the field produced byimpulses passed through said winding.

13. In combination in an instrument for measuring high-potentialimpulses, a permanent magnet, a coil rotatable in the field of saidmagnet, means for maintaining said coil at the same potential withjuxtaposed parts, and means for indicating the extent of movement ofsaid coil under the influence of impulses passed therethrough.

14. In combination in an instrument for measuring electrical impulses, apermanent magnet, a coil adapted to rotate in the field of said magnet,a condenser in shunt to said coil, and means for indicating the extentof movement of said coil under the influence of impulses passedtherethrough.

15. In combination in an instrument for measuring high-potentialimpulses, a permanent magnet, a coil rotatable in the field of saidmagnet, means for maintaining said coil at the same potential withjuxtaposed parts, a condenser in shunt to said coil, and means forindicating the extent of movement of said coil under the influence ofimpulses passed therethrough.

16. In combination in an instrument for measuring high-potentialimpulses, a permanent magnet, a coil adapted to rotate in the field ofsaid magnet, means for maintaining said coil at the same potential withjuxtaposed parts, a non-inductive resistance in shunt to said coil, andmeans for indicating the extent of movement of said coil under theinfluence of impulses passed therethrough.

17. In combination in an instrument for measuring high-potentialimpulses, a permanent magnet, a coil rotatable in the field ol saidmagnet, means for maintaining said coil at the same potential withjuxtaposed parts, non-inductive resistance in shunt to said coil, acondenser in shunt to said coil, and means for indicating the extent ofmovement of said coil under the influence of impulses passedtherethrough.

18. In combination in an instrument for measuring electrical impulses, apermanent magnet, a coil adapted to rotate in the field of said magnet,a resistance in shunt to said coil, a condenser in shunt to said coil,and means for indicating the extent of movement of said coil under theinfluence of impulses passed therethrough.

19. In combination in an instrument for measuring high-potentialimpulses, a permanent magnet, a coil adapted to rotate in the field ofsaid magnet, means for maintaining coil at the same potential withjuxtaposed parts, a condenser in shunt to said coil, a resistance inshunt to said coil, and means for indicating the extent of movement ofsaid coil under the influence of impulses passed therethrough.

20. In combination in an instrument for measuring electrical impulses,means for producin a magnetic field, a coil rotatable in said held,means for damping said coil, means for maintaining said coil and dampingmeans at the same potential, a condenser in shunt to said coil, andmeans forindicating the extent of movement of said coil under theinfluence of impulses passed therethrough.

21. In combination in an instrument for measuring high-potentialimpulses, means for producing a magnetic field, a coil rotatable in saidfield, means for maintaining said coil at the same potential withjuxtaposed parts, a condenser in shunt to said coil, and means forindicating the extent of movement of said coil under the influence ofimpulses passed therethrough.

22. In combination in an instrument for measuring high-potentialimpulses, means for producing a magnetic field, a winding associ atedwith said lield, means for maintaining said winding at the samepotential with juxtaposed parts, a condenser in shunt to said winding,and means for indicating the extent of reaction between said magneticfield and the field produced by impulses passed through said. Winding.

23. In combination in an instruu'ient for measuring high-potentialimpulses, means for producing a magnetic field, a winding associatedwith said means, means for maintaining said Winding at the samepotential with juxtaposed parts, a resistance comprising ahighlyinsulated conductor non-inductively wound, and means forindicating the extent of reaction between said magnetic field and thefield produced by impulses passed through said winding.

24. In combination, a source of high-potential impulses, a translatingdevice supplied thereby, a winding connected with the circuit of saidtranslating device, means associated with said winding for producing amagnetic field, means for maintaining said winding at the same potentialwith juxtaposed parts, and means for indicating the extent of reactionbetween said magnetic field and the field produced by the impulsespassed through said winding.

25. In combination, a source of high-potential impulses, a translatingdevice supplied thereby, a winding connected with the circuit of saidtranslating device, means associated with said winding for producing amagnetic field, means for maintaining said winding at the same potentialwith juxtaposed parts, a condenser in shunt to said winding, and meansfor indicating the extent of reaction between said magnetic field andthe field produced by the impulses passed through said winding.

26. In combination, a source of high-potential impulses, a translatingdevice supplied thereby, a coil connected with the circuit of saidtranslating device, a permanent magnet in whose field said coil isrotatable, means for maintaining said coil at the same potential withjuxtaposed parts, a condenser in shunt to said coil, and means forindicating the extent of movement of said coil under the influence ofimpulses passed therethrough.

27. In combination, a circuit, a translating device connected with saidcircuit, a source of positive and negative impulses connected with saidcircuit, means for preventing the passage through said circuit of otherthan unidirectional impulses, a coil connected with said circuit, apermanent magnet in whose field said coil is rotatable, a condenser inshunt to said coil, and means for indicating the extent of movement ofsaid coil under the influence of impulses passed therethrough.

28. In combination, a circuit, a secondary of an induction -coilconnected therewith, means connected with said circuit for preventingthe passage of other than unidirectionalimpulses, an X.-ray tubeconnected with said circuit, a coil connected with said circuit, apermanent magnet in Whose field said coil is rotatable, means formaintaining said coil at the same potential with juxtaposed parts, acondenser in shunt to said coil, and means for indicating the extent ofmovement of said coil under the influence of impulses passedtherethrough.

29. In combination, a circuit, the secondary of an induction-coilconnected therewith, an X-ray tube connected with said circuit, aspark-gap in said circuit between said secondary and said X-ray tube,means in said circuit for preventing a coil connected with said circuit,a permanent magnet in whose field said coil is rotatable, means formaintaining said coil at the same potential with juxtaposed parts, acondenser in shunt to said coil, and means for indicating the extent ofmovement of said coil under the influence of impulses passedtherethrough.

30. In combination, a circuit, the secondary of an induction-coilconnected therewith, an X-ray tube connected in said circuit, anelectrical measuring instrument connected in said circuit, means formaintaining the winding of said instrument at the same potential withjuxtaposed parts, and a condenser in shunt to said winding.

HOMER CLYDE SNOOK.

I/Vitnesses:

JOHN CONNELL, F. M. BRYAN.

